Antioxidant activities of different fractions of polysaccharide purified from pulp tissue of litchi (Litchi chinensis Sonn.)

Three fractions of water-soluble polysaccharide fractions, coded as LFP1, LFP2 and LFP3, were isolated and purified from litchi pulp by DEAE-52 cellulose anion-exchange column and Sephadex G-100 gel-permeation column. Their chemical and physical characteristics were determined by chemical methods, gas chromatography, IR spectrophotometer and gel-permeation chromatography (GPC) with a model 410 refractive index detector. Antioxidant activities of these fractions were investigated using various in vitro assay systems. Results indicated that LFP1 was composed of arabinose, ribose, galactose and glucose, while LFP2 comprised arabinose, rhamnose and glucose. LFP3 was a heteropolysaccharide bounded with protein (2.6%) and composed of arabinose, rhamnose, galactose and glucose. The molecular weights of LFP1, LFP2 and LFP3 were 11.6 × 104, 3.1 × 104 and 2.9 × 104 Da, respectively. LFP3 showed the highest antioxidant activities among the three fractions of polysaccharides, and could be explored as a novel potential antioxidant.